Why are my files changing size on their own

So this is a strange question let me see if I can explain. I design email blast at work and they are always 740 px wide but for some reason they keep changing to 700 without me doing it. Is there some key command i am hitting by accident to be causing this?

I never notice it until I go to upload the slices and then I have to go back and resize it and re save the slices which sometimes messes up the numbering on the slices. Any help is appreciated.

The only way you could change a file size while saving is using SaveForWeb and telling it to resample the image. Otherwise Photoshop saves the file with the exact pixels you have in your document - which has to have the same pixel size.

Some email clients (like AOL and Apple mail) can mangle image sizes when they are embedded in email.

That's the thing it is changing the size of the document on me without me going in and doing it myself. This has happened several times. This is why I asked if maybe I am hitting a key or key command by accident that may be doing it.

I create a file it is 740 px wide. I then use that "template" to create multiple files with different deals and contact info. A few of those files end up 700 px wide when I did not change the image size or canvas size. What am i doing wrong or is this a system glitch.

I create a new file 740px wide it becomes a "template" for several files. I NEVER change the document or canvas size. I go through and make changes to text and images and save it several time under different names. Somehow one or two of these other files end up 700px wide without me doing anything so don't tell me photoshop can't do it when it is.

Again, Photoshop cannot change the size of the document unless you explicitly tell it to. Somewhere, you are making a mistake in your work. This is not a Photoshop glitch - this is something you are doing in your workflow that changes the size of your document or only saves part of your document (like slices).

So back to my original question is there some sort of key command I may be hitting that is resizing. I understood that I either had to open the changes through image>image size/ canvas size. Or using the crop tool and setting the size is there another way to change the size I may be doing inadvertently.